Bicycle suspensions have become popular because they allow riders to ride more comfortably over rough terrain, and with more control in difficult circumstances. Rear suspension systems are particularly important in improving comfort and safety, and have been developed to the point of allowing more than 6" of vertical suspension travel of the rear wheel. The onset of downhill mountain bike racing in the early 1990's prompted the design of rear suspensions having large amounts of suspension travel.
When the rear suspensions designed for downhill mountain bike racing are transferred to more general types of mountain bikes, the forward motive force generated by the rider through the drive train is partially used to activate the suspension system. The partial activation of the rear suspension reduces the efficiency with which the rider's pedaling energy is transmitted to the forward movement of the bicycle. While this phenomenon occurs in downhill style mountain bikes, it is not an important issue because of the particular downhill riding style. When the energy loss phenomenon occurs in a more general type of mountain bike, the resulting inefficiencies can drastically affect performance.
In addition, the rear suspension designs presently available often have a changing energy absorption rate through the suspension travel which inhibits the rider's use of the top portions of the suspension travel. In other words, as the rear suspension moves through the designed travel range, the suspension becomes more and more stiff and it becomes more difficult to utilize the end of the suspension travel than to utilize the early portions of the suspension travel. As the suspension travel is compressed the harder it becomes to compress further.
There has been an increased interest to have active rear suspensions which provide a great deal of vertical travel, but that are more efficient in transferring the pedaling force of the rider to the forward movement of the bicycle without losing energy to compression of the rear suspension. Bikes having these types of rear suspensions are considered all-around, cross country or free-ride type mountain bikes.
There is a continuing need in the art for an improved rear suspension which is more efficient in transferring the pedaling force of the rider to the forward movement of the bike, and to minimize the energy lost in compressing the rear suspension.